In a bowl, combine warm milk, yeast, and 1 teaspoon of sugar. Let it sit for 5-10 minutes until it becomes foamy.

In another bowl, mix the remaining sugar, eggs, softened butter, and salt. Add the yeast mixture and 3 cups of flour, stirring until a shaggy dough forms. Gradually add the rest of the flour.

Knead the dough for 5-7 minutes until it is smooth.

Place the dough in an oiled bowl, cover it, and let it rise for 1 to 1.5 hours until it doubles in size.

In a bowl, mix the brown sugar, 2 tablespoons of cinnamon, and melted butter to form a paste for the filling.

Roll the dough into a rectangle. Brush it with melted butter, spread the filling over it, then roll it into a log. Shape the log into a ring.

Put the ring on a baking sheet, cover it, and let it rise for another 30-45 minutes. Preheat the oven to 375°F (190°C).

Bake for 25-35 minutes until it is golden brown. Let it cool on a wire rack.

Whisk together powdered sugar, milk, and vanilla to make the glaze. Drizzle this glaze over the cooled cake and sprinkle with sanding sugar.

Slice the cake into thick pieces and serve at room temperature.